Such housings are frequently embodied in two parts, with a first part of the housing being twistable with respect to a second part through a predetermined angular range, in order to rotate, for example, display or operating elements, which are arranged on the first housing part, into a desired orientation. Since cable frequently extends between the first and second housing parts, the angular range must be limited, in order to prevent a damaging of the cable or components connected therewith.
Known differential pressure transmitters, available under the name “Deltabar”, exhibit a twist limiting feature which may be described as follows. The first housing part has a tubular, first connecting flange with an internal thread, which is screwed onto an external thread of a complementary, second connecting flange of the second housing part. From the cylindrical, outer lateral surface of the second connecting flange, a stop lug extends radially outwards, in a section which is axially separated from the first connecting flange. Following the screwing of the first connecting flange onto the second connecting flange, a metal tongue is mounted on the outer, lateral surface of the first connecting flange. The metal tongue extends in the axial direction across the first connecting flange and beyond, and overlaps the stop lug in the axial direction. Twist of the second connecting flange with respect to the first connecting flange is, as a result, limited in both directions by the hitting of the metal tongue on the stop lug. Although this described, twist limiting feature is reliable, nevertheless its manufacture and mounting are involved.
The described problem concerns not only pressure sensors, but, quite generally, all sensors of the technology of industrial process measurements, especially flow rate sensors, viscosity sensors, fill level sensors, pH-sensors and other potentiometric sensors, temperature sensors, moisture and humidity sensors, gas sensors and turbidity sensors.